Filter Body

ABSTRACT

A filter body has a longitudinal axis and a first end face and a second end face opposite the first end face in a direction of the longitudinal axis. The filter body has a zigzag-folded filter medium arranged about the longitudinal axis, wherein the filter body has an inner circumference and an outer circumference and fold edges of the filter medium are positioned on the inner circumference and/or the outer circumference. The filter body further has a securing coil of at least one circumferentially extending thread applied onto the outer circumference. The fold edges have, at least over sections thereof, several embossments arranged such that the fold edges that are next to each other are secured relative to each other by the embossments.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/815,214 filed: Apr. 23, 2013. This application claims foreignpriority under 35 USC 119(b) to prior filed German patent applications10 2013 002 274.6 filed Feb. 12, 2013; 10 2013 002 275.4 filed Feb. 12,2013; 10 2013 002 277.0 filed Feb. 12, 2013; 10 2013 002 278.9 filedFeb. 12, 2013; and 10 2013 002 276.2 filed Feb. 12, 2013, the entirecontents of the aforesaid U.S. Provisional Application and the aforesaidGerman patent applications being incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention concerns a filter body, in particular for use as an airfilter of an internal combustion engine, as well as a filter elementwith a filter body and a filter system for installation of such a filterelement.

WO 2009/047196 A1 discloses a filter element for internal combustionengines that is comprised of a zigzag-folded filter medium in aconcentric shape, a first open or closed end disk arranged on an endface and a second end disk arranged on the oppositely positioned endface wherein the end disk has a concentric opening and extendssubstantially as a circular ring across the folds of the filter medium.The filter element has annular beads and sealing grooves for sealing thefilter element in a housing.

Moreover, WO 2009/047196 A1 discloses a filter system with a filterelement. This filter system serves in particular for filtration of theintake air of an internal combustion engine and is comprised of ahousing and a removable cover for receiving the filter element. Thefilter system has two annular grooves that communicate with the sealingcontours of the filter element in the area of the sealing action.

In principle, the reliable sealing action of a filter element in ahousing is important for reliable operation. The sealing action shouldbe temperature-resistant and vibration-resistant. The sealing action ofthe filter element must be ensured also in connection with devices orfacilities that are exposed to strong vibrations or impacts. At the sametime, the filter element should, if possible, contain no metallic partsso that it can be thermally disposed of without problems. In order toensure these properties, a high mechanical stability of the filterelement, whose filter medium usually consists of paper or nonwoven, isrequired for the duration of the entire service life.

It is therefore an object of the invention to design a filter body for afilter element such that a high mechanical stability of the filterelement for the duration of its service life is ensured, even underunfavorable environmental conditions such as moisture and/or greattemperature fluctuations.

A further object of the invention is to provide a filter system withsuch an exchangeable filter element that exhibits a high mechanicalstability for the duration of its service life, even under unfavorableenvironmental conditions such as moisture and/or great temperaturefluctuations.

SUMMARY OF THE INVENTION

In accordance with the present invention, this is achieved according toone aspect of the invention with a filter body that has fold edgesarranged on the inner and/or outer circumference of the filter body,wherein the fold edges, at least over sections thereof, have severalembossments that secure neighboring fold edges relative to each otherand wherein a securing coil of at least one circumferentially extendingstrip or thread is provided on the outer circumference of the filterbody.

According to another aspect of the invention, a filter system with sucha filter body is provided.

Accordingly, a filter body having a longitudinal axis and two end facesis proposed that comprises a filter medium that is arranged about alongitudinal axis a zigzag-folded shape and has an inner circumferenceand an outer circumference. The fold edges of the zigzag shape arearranged on the inner and/or outer circumference of the filter body andthe fold edges, at least over sections thereof, have several embossmentswhich secure neighboring fold edges relative to each other and wherein asecuring coil of at least one circumferentially extending strip orthread is applied to the outer circumference of the filter body

The embossments can be applied, for example, by rolling of the foldedfilter medium wherein the fold edges of the folded filter medium aredepressed at sequentially arranged fold edges in a defined way. The foldedge widens at the rolled location and can thus be supported on theembossment of the neighboring fold edge. In this way, the filter bodycan be advantageously stabilized relative to deformation. Theembossments can be arranged as a circumferential structure on thecircumferential surface of the filter medium at the same axial height.Conceivable is also to design the embossments so as to alternate on thecircumferential surface with areas that are not embossed, instead ofproviding circumferentially arranged embossments. In this case, it isadvantageous when embossed and non-embossed areas at the circumferenceare staggered relative to each other for axially neighboringembossments.

By supporting the fold edges by means of a combination of embossments onthe outer circumference and/or on the inner circumference of the filterbody, i.e., at the incoming flow side and/or at the outgoing flow sideof the filter body, and of securing coils, the folds are uniformlydistributed in the circumferential direction. By combination of theembossments at the incoming flow area and/or outgoing flow area of thefilter body and the fixation by the securing coil, an advantageouslyarranged fold position and fold distribution results. This combinationof measures provides straightness of the folds in their length-wiseextension in the direction of the longitudinal axis of the filter bodywhich is very beneficial relative to variants employing a support actionsolely by embossments or solely by spiral securing coils. Effects likecompaction, slanted or tilted positioning, or wave formation of thefolds of the filter medium by environmental influences, such as water,moisture in the air, temperature and the like are significantly reducedwith this arrangement. The embossments ensure a uniform spacing of thefolds and thus provide an optimal passage for the incoming medium.Moreover, a defined dust pocket remains that counteracts compaction ofthe folds. The securing coil secures the fold spacing that is adjustedby the embossments and ties the filter medium to a compact filter body.The stiffness of the filter body remains intact in this way. Inaddition, the filter body absorbs, without fold deformation, the axialclamping forces occurring upon installation of a filter elementconstructed from the filter body in a housing.

In a beneficial embodiment, the filter medium can be made of paper,paper reinforced with plastic fibers, and/or plastic-coated paper. Theuse of these materials as a filter medium represents a very economicpossibility for realizing such a filter element. At the same time, thedescribed shaping provides a stable arrangement so that aself-supporting configuration of the filter body and thus beneficialmounting properties are provided.

Advantageously, the securing coil may comprise at least one strip orthread extending in the direction of the longitudinal axis on the outercircumference of the filter body. With additional strips or threadsperpendicular to the circumferentially extending threads or strips onthe outer circumference of the filter body, the securing coil can beadditionally reinforced and is thus suitable for very roughenvironments. Also, very large and heavy filter bodies, for example, foruse in construction machines or agricultural machinery can beadditionally stabilized in this way.

In one embodiment, one or several strips or threads are wound in a coilshape about the outer circumference to form the securing coil. In thisconnection, it can be advantageous to provide areas with differentpitch. For example, in the area adjacent to the closed end disk, thethread can be wound with reduced pitch so that the threads or strips arecloser to each other, for example, spaced by less than 2 cm (0.8inches), preferably approximately 1 cm (0.4 inches). In this way, inthis area a grip or handling-resistant zone can be provided in which thefilter medium is reinforced for absorbing the manually applied operatingforces when exchanging the filter element.

Expediently, the securing coil can be comprised of plastic-impregnatedthread or strip. Such threads or strips have the advantage that they aremoisture-resistant, have an excellent long term behavior, and alsoexhibit additional strength so that the filter body as a whole is morestable.

In an advantageous embodiment, the securing coil can be glued onto thefilter medium. The strip or thread of the securing coil can be woundfrom a bath of hot-melt adhesive onto the filter body. When the filterbody with securing coil is subsequently subjected to a heat treatment,the hot-melt adhesive can fuse with the filter medium and cure and, inthis way, imparts to the securing coil and the filter body a significantstrength. Alternatively, other curing methods, depending on the employedglue, can be used. For example, curing methods employing UV light can beused also.

Advantageously, the filter body can have at least at one end face areinforcement ring. In this way, the filter body is provided with afurther stabilizing element that, together with the combination ofembossments and securing coil, serves for improved absorption of theaxial clamping forces upon installing a filter element made therefrom ina housing.

The invention concerns according to a further aspect a filter elementthat comprises a filter body, a first open or closed end disk that isarranged at an end face and a second end disk that is arranged at thesecond oppositely positioned end face as well as a support tubeconcentrically arranged relative to the longitudinal axis and extendingbetween the first and second end disks. Such a filter element is readyto be mounted and can be used in a filter system, for example, of aninternal combustion engine. In this context, the two end disks and thesupport tube serve for mounting and sealing in the housing of the filtersystem.

Advantageously, the second end disk, like the first end disk, can becomprised of polyurethane foam or an elastomer. Of course, there is alsothe possibility to produce the end disk from several plastic componentsin order to ensure an optimal deformability across a wide temperaturerange, which may be encountered when using the filter element inpractice. Accordingly, thermoplastic synthetic materials are notexcluded. Both end disks can be fused (welded) or glued to the filterbody in order to provide a stable connection.

Expediently, the first end disk can have a radial seal relative to thehousing. This has the advantage that in addition to an excellent sealingaction and thus a safe filtering action, due to the radial seal a radialguiding of the filter element in the housing can be effected and, inthis way, a very stable securing action of the filter element in thehousing is provided.

Expediently, the filter element can be used as an air filter, inparticular as an air filter of an internal combustion engine. The safeoperation of internal combustion engines is based also on a safe andfavorable filtering of the intake air for combustion. The disclosedfilter element provides an economic possibility for this purpose.

Advantageous is also the use of the filter element as a particulatefilter, in particular as a diesel particulate filter of an internalcombustion engine. Here also safe mounting and economic exchangeabilityof the described filter element are of decisive importance.

The invention concerns, according to a further aspect, a filter systemwith a filter element, comprising a housing which is substantiallyconcentrically configured about a longitudinal axis; a cover that closesoff the housing and that is also concentrically designed relative tolongitudinal axis; an inlet arranged on the housing and/or the cover forsupply of the medium to be filtered, in particular air; wherein on thehousing, concentric to the longitudinal axis, an outlet for dischargingthe filtered medium is provided; wherein on the housing in the area ofthe outlet a sealing contour is provided which corresponds with theradial seal of the first end disk of the filter element; wherein thefilter element is exchangeably arranged in the housing of the filtersystem. The important advantage of such a filter system resides in thevery safe and stable installation of the filter element as well as inthe economic exchangeability or replacement of the filter element in aservice situation. Especially for a short service life, as in use in thefield of agricultural or construction machinery, the fastexchangeability is of great importance.

Advantageously, in the area of the inlet of the filter system, a cycloneseparator can be provided and a dirt outlet can be provided on thehousing or on the cover. This cyclone separator is comprised of aguiding geometry that causes the medium to be filtered to rotate. Due tothis rotation, the dirt is concentrated in the area of the housing walland is discharged at a suitable location by means of the dirt outlet. Bypreseparation of most of the dirt from the air to be filtered, theservice life of the actual filter element can be decisively prolonged.

According to a further embodiment of the invention, a secondary elementcan be arranged in the interior of the filter element. The secondaryelement that may be comprised of a support structure that is coveredwith a permeable filter medium, for example, a nonwoven, has the task ofkeeping closed the outlet of the filter system during exchange of thefilter element so that no dirt can penetrate into this area while thefilter element is cleaned or replaced. The secondary element in apreferred embodiment is connected by a screw connection with the housingand is provided with a seal relative to the housing.

BRIEF DESCRIPTION OF THE DRAWING

Further advantages result from the following description. In thedrawing, exemplary embodiments of the invention are illustrated withoutbeing limiting. The drawings, the description, and the claims containseveral features in combination. A person of skill in the art willconsider the features expediently also individually and will combinethem to other meaningful combinations.

FIG. 1 shows in a perspective view a filter system according to anembodiment of the invention with tangential inlet, central outlet, anddirt outlet at the bottom side.

FIG. 2 shows in a perspective view a filter system according to anembodiment of the invention with radial inlet and central outlet.

FIG. 3 is a longitudinal section of the filter system according to anembodiment of the invention with tangential inlet, central outlet, anddirt outlet at the bottom side.

FIG. 4 is a schematic illustration of a filter body according to theprior art with embossments on the inner and outer circumference of thefilter body.

FIG. 5 is a schematic illustration of a filter body according to anembodiment of the invention with embossments on the inner and outercircumference of the filter body as well as a securing coil on the outercircumference.

FIG. 6 is a schematic illustration of a filter body according to afurther embodiment of the invention with embossments on the inner andouter circumference of the filter body, a securing coil on the outercircumference, and a reinforcement ring at an end face.

FIG. 7 is a filter element made of a filter body according to FIG. 5

FIG. 8 is a longitudinal section of the filter element according to FIG.7.

FIG. 9 is an enlarged view of a part of the longitudinal section throughthe filter element according to FIG. 7.

In the Figures, same components or components acting in the same way areidentified with the same reference characters. The Figures show onlyexemplary embodiments and are not to be understood as limiting.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows in a perspective view a filter system 100 according to anembodiment of the invention with tangential inlet 102, central outlet104 at an end face of the housing, and a dirt outlet 106 at the bottomside. Illustrated is a round filter configuration that is comprised of ahousing 108 that is closed off by a cover 110, for example, by a screwconnection or bayonet coupling connection. When used as an air filtersystem, dust-laden air flows into the inlet 102 that is arrangedtangential to the air filter element arranged in the interior of thehousing so that the air in the interior of the housing 108 is caused torotate by an incoming flow protector at the filter element. Filterelement and incoming flow protector are not illustrated in the drawing.Due to the cyclone effect caused by the rotational movement of the air,centrifugal forces are acting on the dust particles contained in theincoming air so that the dust particles are partially separated at thehousing wall and can be discharged by means of dirt outlet 106 from thefilter system 100. In this way, the filter element is loaded less andthe service life of the filter element is increased. The purified aircan be discharged via the central outlet 104 from the housing 108.

FIG. 2 shows a perspective view of a filter system 100 according to anembodiment with inlet 102 at the cover and central outlet 104.Illustrated is also a round filter configuration comprised of a housing108 that is closed off by a cover 110. The inlet through which thedust-laden air can enter the housing is in this case arranged centrallyabove the filter element installed in the interior. The outlet 104through which the purified air can flow out is centrally arranged, asalso shown in FIG. 1.

Such filter systems as illustrated in FIGS. 1 and 2 are usually employedin construction machinery and agricultural machinery. They arecharacterized by great robustness and have a short service life due totheir high dust load. A filter system 100 with loaded filter elementmust be able to tolerate a weight increase of 10 kg or more.

In FIG. 3 a longitudinal section of the filter system 100 according toan embodiment of the invention with tangential inlet 102, central outlet104, and dirt outlet 106 at the bottom side is illustrated. The housing108 of the filter system 100 is closed off by a cover 110. The filterelement 10 that is comprised of a support tube 14 concentricallyarranged about longitudinal axis L and the filter body 12 is provided attwo opposite end faces 15, 17 with first and second end discs 16, 18that are, for example, made of castable polyurethane, in particularpolyurethane foam, or an elastomer. The second end disk 18 and thesupport tube 14 of the filter element 10 may be configured together as amonolithic component. The filter body 12 can be folded, for example, ina zigzag shape, can be of an annularly closed configuration, and can becomprised of paper, paper reinforced with plastic fibers, and/or ofplastic-coated paper.

The second end disk 18 whose stability is increased by a reinforcementplate 30 has support knobs 20 which, upon installation into the housing108 provided for receiving the filter element, are supported axially aswell as radially on the housing 108 by contacting an inner cover contour114 of the cover 110. On the oppositely positioned end face 15 of thefilter element 10, a radial seal 26 is provided on the first end face 16whose stability is increased by the reinforcement ring 31. With theradial seal 26, the filter element 10 is radially supported via sealingcontour 116 on the housing 108 and seals the unfiltered air chamberrelative to the filtered air chamber. The filter element 10 is thusaxially as well as twice radially clamped relative to the housing 108.

Dust-laden air can be flowing in through the inlet 102 in the directionof arrow 40; the inlet 102 is in this case illustrated as a tangentialinlet and enables, due to the rotational movement of the air which iseffected by the cyclone separator 36, a cyclone operation. Dustparticles, partially pre-separated by the rotational movement, candeposit on the inner housing wall and by means of the dirt outlet 106,in case of installation of the filter housing 108 in horizontalposition, can be discharged in downward direction by the force ofgravity from the filter system 100. In operation, the air flows, afterpartial separation of the dust particles, through the filter body 12 inthe direction of arrows 42, 44 into the interior 50 of the filterelement. Dust particles are retained within the filter medium, beginningat a certain size of the particles that depends on the filter medium.Depending on the dust load, the filter element 10 must be exchangedafter a certain operating time.

Via the outlet 104, the filtered air flows in the direction of arrow 46out of the system. In the interior 50 of the filter element 10, i.e., inthe clean air area, a secondary element 28 is provided that issubstantially comprised of a support structure with a filter medium thathas a relatively high permeability, for example, a nonwoven, and uponexchange of the filter element 10 remains in the housing 108 forprotecting the downstream air guiding passage, for example, of aninternal combustion engine, against penetration of dust particles andother objects. The secondary element 28 is fixedly screwed on by ascrew-on part 32 onto the outlet-side component of the housing 108 andis sealed by a radial seal.

FIG. 4 shows a purely schematic illustration of a filter body 12 withend faces 52, 54 according to the prior art with embossments 64 on theinner and outer circumference 58, 60 of the filter body 12. The filterbody 1, illustrated purely schematically in the shape of a hollowcylinder of the filter medium 56 without providing details of thezigzag-folded filter medium, has embossments 64 which are arranged in anannular shape on the inner as well as outer circumference 58, 60 of thefilter body 12. In principle, these embossments 64 in the filter medium56 can be produced prior to producing the filter body 12 in thesemi-finished product, i.e., in the folded paper. Conceivable is howeveralso an embossment process by means of suitable embossment stamps afterthe filter body 12 has been converted into its final shape.

In a concrete embodiment, the filter body 12, with its longitudinal axisL and two end faces 52, 54, comprises a filter medium 56 that isarranged about longitudinal axis L and is folded in a zigzag shape andprovided with an inner circumference and an outer circumference 58, 60.Fold edges 62 are positioned on the inner and/or outer circumference 58,60 of the filter body 12 and the fold edges 62 at least partially haveseveral embossments 64 which secured neighboring fold edges 62 relativeto each other.

It is beneficial when the filter medium 56 is made of paper, paperreinforced with plastic fibers, and/or plastic-coated paper.

FIG. 5 shows also in a purely schematic illustration a filter body 12with the end faces 52, 54 according to an embodiment of the inventionwith embossments 64 on the inner and outer circumference 58, 60 of thefilter body 12 as well as a securing coil 66 on the outer circumference60. In addition to the annular embossments 64, annular threads of asecuring coil 66 are provided. The securing coil is provided on theouter circumference 60 of the filter body 12 for reinforcement of theentire composite. The inner circumference 58 of the filter body 12 issimply embossed with embossments 64.

In the concrete embodiment of the invention, the filter body 12 isprovided in addition to the embossments 64 with a securing coil 66 of atleast one circumferentially extending thread or strip 68 on the outercircumference 60 of the filter body 12. Further, the securing coil 66can have at least one thread 68 perpendicular to the circumferentiallyextending threads in the direction of the longitudinal axis L on theouter circumference 60 of the filter body 12 in order to therebyadditionally stiffen or reinforce the filter body 12. The securing coil66 can be expediently comprised of a plastic-impregnated thread or stripin order to protect the thread/strip from the effects of moisture. Thesecuring coil 66 can moreover be secured on the filter medium 56 by ahot-melt adhesive connection after application on the outercircumference 60 of the filter body 12.

In FIG. 6, a filter body 12 according to a further embodiment of theinvention is illustrated purely schematically. The filter body 12 isprovided with embossments 64 on the inner and outer circumference 58, 60of the filter body 12, a securing coil 66 on the outer circumference 60,as well as a reinforcement ring 70 on an end face 54. In one area of thefilter body 12, an improper handling protector 72 (protector to preventdamage by improper handling) in the form of, for example, a film isillustrated by means of which the filter body 12 as a finished filterelement can be installed in and removed from a housing by hand.

FIG. 7 shows a filter element 10 comprised of a filter body 12 accordingto FIG. 5. The filter body 12 is in this context provided with a firstopen or closed end disk 16 arranged at an end face 15 and a second enddisk 18 at the opposite end face 17 that effect an additionalreinforcement of the filter element 10 and also, as elastic elements(they are comprised usually of polyurethane form or an elastomer),enable installation and clamping of the filter element 10 in a housing.Moreover, it has a support tube 14 that is concentric to thelongitudinal axis L and extends between the first and second end disks16, 18. The first end disk 16 has a radial seal 26 for sealing relativeto a housing.

In FIG. 8 a longitudinal section of a filter element 10 according toFIG. 7 is illustrated. The section through the filter body 12 that ispositioned between the two end discs 16, 18 that may be comprised e.g.of injection-molded polyurethane or elastomer has embossments 64 atregular spacings relative to each other. The embossments 64 are embodiedas recesses in the filter medium 56. Also provided are strips or threadsof a securing coil 66 applied on the filter medium 56. In this way, asignificant reinforcement of the filter body 12 even in case ofintroduction of some moisture and in case of great temperaturefluctuations of the filtered air is provided.

FIG. 9 shows an enlarged view of a part of the longitudinal section ofthe filter element 10 according to FIG. 7. In this illustration, therecesses of the embossments 64 as well as the applied threads of thesecuring coil 66 can be seen more clearly.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the inventive principles, it will beunderstood that the invention may be embodied otherwise withoutdeparting from such principles.

What is claimed is:
 1. A filter body having a longitudinal axis and afirst end face and a second end face opposite the first end face in adirection of the longitudinal axis, wherein the filter body is comprisedof a zigzag-folded filter medium arranged about the longitudinal axis,wherein the filter body has an inner circumference and an outercircumference and fold edges of the filter medium are positioned on theinner circumference and/or the outer circumference, and is furthercomprised of a securing coil of at least one circumferentially extendingthread applied onto the outer circumference, wherein the fold edgeshave, at least over sections thereof, several embossments arranged suchthat the fold edges that are next to each other are secured relative toeach other by the embossments.
 2. The filter body according to claim 1,wherein the filter medium is paper, paper reinforced with plasticfibers, and/or plastic-coated paper.
 3. The filter body according toclaim 1, wherein the securing coil comprises at least one threadextending in the direction of the longitudinal axis on the outercircumference.
 4. The filter body according to claim 1, wherein thesecuring coil is comprised of a plastic-impregnated thread.
 5. Thefilter body according to claim 1, wherein the securing coil is gluedonto the filter medium.
 6. The filter body according to claim 1, furthercomprising a reinforcement ring disposed on at least one of the firstand second end faces.
 7. A filter element comprising: a filter bodyaccording to claim 1; a first end disk arranged at the first end face ofthe filter body and a second end disk arranged at the second end face ofthe filter body; a support tube that is concentrically arranged relativeto the longitudinal axis of the filter body and extends between thefirst and the second end disks.
 8. The filter element according to claim7, wherein the second end disk is comprised of a polyurethane foam or anelastomer.
 9. The filter element according to claim 7, wherein the firstend disk has a radial seal for sealing relative to a housing.
 10. Thefilter element according to claim 7 as an air filter.
 11. The filterelement according to claim 7 as a filter element of an internalcombustion engine.
 12. The filter element according to claim 7 as aparticulate filter.
 13. The filter element according to claim 7 as adiesel particulate filter of an internal combustion engine.
 14. A filtersystem comprising; a housing that is configured substantiallyconcentrically about a longitudinal axis; a cover closing off thehousing and concentrically configured relative the longitudinal axis; afilter element according to claim 7 disposed exchangeably in thehousing; an inlet arranged at the housing and/or the cover wherein amedium to be filtered is supplied via the inlet; an outlet arrangedconcentrically on the housing relative to the longitudinal axis, whereinfiltered medium is discharged via the outlet; wherein a sealing contouris provided on the housing in the area of the outlet, wherein thesealing contour corresponds with a radial seal of the first end disk ofthe filter element.
 15. The filter system according to claim 14, furthercomprising a cyclone separator disposed in the area of the inlet andfurther comprising a dirt outlet disposed at the housing or at thecover.
 16. The filter system according to claim 14, further comprising asecondary element arranged in an interior of the filter element.
 17. Thefilter system according to claim 16, wherein the secondary element isconnected to the housing and remains within the housing when the filterelement is exchanged.